Many modern systems utilize power in a pulsed delivery mode, repeatedly supplying energy to an energy storage element, typically charging a storage capacitor, and rapidly delivering the stored energy into a load. For example, many medical lasers operate by delivering optical energy in a rapid-fire series of short laser bursts. Applications include eye surgery, cosmetic dermatology including hair removal, dentistry removing hard and soft tissue, and general surgery. These bursts are generated by rapidly discharging an energy storage element such as a capacitor into typically a flash lamp or laser diode array. The capacitor is repeatedly charged by a power supply unit (PSU) and discharged into the load. Other similar pulsed-mode power supply applications include strobe lights, such as those used for stop-motion photography, and pulsed beacons, such as those used on broadcasting towers, tall buildings, aircraft, laser rangefinders, laser designators, pulsed electromagnets, pulse forming networks, etc. In many applications, the capacitor is not completely discharged.
To meet specifications requiring reduced levels of harmonics caused by input currents of power supplies, a power factor corrector circuit is required. As is known, a power factor corrector circuit ensures that the AC current waveform follows the magnitude of the AC voltage supply to give a close to unity power factor. In addition, the AC current and voltage waveform, normally sinusoidal in shape, should be free from sudden changes or transients due to load surges, as such distortion can also affect the power factor and cause an increase in measured rms current drawn.
In typical prior art, a boost converter generates a regulated DC voltage on a capacitive storage bank from which the capacitor charging power converter operates. This requires essentially two power supplies with two sets of magnetic components, power switches, diodes etc., both sets capable of operating at or above the maximum output power level.
Reference is made to commonly-owned U.S. Pat. No. 6,087,811 ('811 patent), incorporated in its entirety by reference herein.